I thought Trine 3 was perfectly serviceable and a good followup to the previous two games. Apparently, I’m the only one? Enjoyed playing it co-op with my wife, as with the others in this series, so I pre-ordered Trine 4 the moment I could (on GOG).
These games are very accessible. Not to say there aren’t any challenging bits, but for the most part it’s a smooth ride. It focuses more on puzzles and Lost Vikings-style problem-solving.